A zinc oxide dispersion is a mixture comprising powdered or finely divided zinc oxide (ZnO) combined with various oils or other coatings. The specific gravity of a typical ZnO dispersion is 3.00–4.00 gm./cc. Many companies manufacture zinc oxide dispersions, e.g., Tiarco Chemical Company, Polychem Dispersions, Bayer Group, and many other raw rubber manufacturers and chemical manufacturers. One example of a zinc oxide dispersion is marketed by Tiarco Chemical Company under the trade name “Octocure 462.” This material is approved by the U.S. Food and Drug Administration for use under the following: 21 C.F.R. Sections 175.105, 175.300, 176.170, 176.180, 176.210, 177.1210, 177.1650, and 177.2600.
It was previously known to use small quantities of zinc oxide dispersion in rubber compounds to serve as an activator in the curing and vulcanization of rubber, as a reinforcing agent adding durability and abrasion resistance, and as a material which aids in the protection of rubber from harmful UV rays. Previously, the normal use level for a zinc oxide dispersion was in the range from about 1% to about 5% by weight in a styrene butadiene rubber (“SBR”) or natural latex compound.
Zinc oxide dispersions were previously added only in small quantities to raw rubber compounds because most raw rubber is intended for uses that a high concentration of a zinc oxide dispersion would degrade. Generally speaking, a vulcanized rubber part is rarely intended to sit idle and function as a weight or weighted item. Instead, most raw rubber, once vulcanized, is intended to give the end product a high tensile strength, a high modulus, resistance to heat and/or to cold, or good elongation. The addition of zinc oxide dispersions is known to reduce the strength, modulus, temperature resistance and elongation of rubber after curing. When only small amounts of zinc oxide dispersion (e.g., 1%–5%) are added to the rubber, the reduction in these properties is generally considered acceptable.
Further, it was heretofore believed that high concentration zinc oxide dispersion rubber compounds would be impractical and undesirable to use because the rubber compound in its raw (i.e., uncured) state was expected to be prone to melting, running and excessive stickiness. Such properties tend to make the raw rubber difficult or expensive to transport, store and handle.
Very heavy rubber compounds, i.e., those having a specific gravity exceeding about 2.0 gm/cc, are known which are hard and inflexible, suitable for use in simulating stationary objects, or for uses such as traffic barrier bases, wheel stops, etc. For example, some rubber compounds are loaded with clays or other high specific gravity filler materials to produce rubber compounds having specific gravities exceeding 5 gm./cc. However, the resulting compounds are not soft or flexible, and they do not easily conform to complex shapes such as the human body. Thus, these previously known heavy rubber compounds are not well suited for use as, e.g., flexible weights for weight suits for exercise and training, flexible scuba diving weights, belts and other items, or flexible rehabilitation devices, all of which require a rubber which is heavy while still being soft, pliable and flexible.
Previously, when soft, pliable and/or flexible rubber weights or other high-specific gravity components were needed, metallic lead, in the form of shot, pellets, or powder was often molded into the component. However, use of metallic lead in rubber components complicated the molding and production process, and lead's toxic properties made it unsuitable for many uses, including children's products, school equipment and sports equipment. Substitution of metallic steel or other non-toxic metals for the lead addressed the toxicity problem, but not the molding and production problems caused when trying to encapsulate metallic particles.
A need therefore exists, for soft, pliable and/or flexible rubber compounds which are non-toxic, contain no metallic particles, but have a high specific gravity.
Wearable weight systems are known comprising a fabric garment, e.g., vest, shirt, shorts, pants, body suit, socks, etc. having one or more pockets distributed across the garment holding weights or weighted pads. Such wearable weight systems allow the wearer to perform exercise or athletic training (e.g., football or basketball workouts) while carrying additional weight, but without unduly impeding the wearer's mobility. The weights and weight pads used for wearable weight systems have heretofore included metal weights, metal-filled rubber weights, and bulky sandbags or shot-filled bags. In some cases, these weights or weight pads were hard and inflexible, risking breakage of the pads or injury to the wearer (or others) during falls, collisions or impacts. In other cases, the prior art weights and weight pads were so thick and bulky that the wearer's mobility was somewhat restricted. In still other cases, the weights or weight pads included lead or other hazardous materials which were inappropriate for use around children or young persons.
A need therefore exists, for a wearable weight system including a garment with one or more pockets containing weights or weight pads of flexible rubber. Preferably, the weights or weight pads of the wearable weight system will contain no metallic components. More preferably, the weights or weight pads of the wearable weight system will contain no hazardous materials.